1. Field of the Invention
The present invention relates to a ski binding, as well as to a ski provided with such a binding.
2. Description of Relevant Information
French Pat. Nos. 2,517,214; 2,478,476; 2,458,299; 2,419,737; and 2,420,359 all relate to "front abutment" type bindings.
This type of binding comprises:
a jaw adapted to receive and retain the front end of a ski boot with respect to a ski. Two lateral wings are provided for this purpose at the rear of jaw. The wings are adapted to grip the boot on both lateral sides thereof; PA0 a support element defining, for the jaw, two frontwardly directed lines of support with respect to the ski, for guiding the lateral pivoting of the jaw. The two lines of support converge upwardly at a point, to define a common plane transverse with respect to the ski, such that lateral pivoting of the jaw with respect to the ski around either one of the lines of support is accompanied by a lifting of the wings of the jaw with respect to the ski; and PA0 an elastic energization mechanism which presses the jaw against the support element and biases the jaw elastically against lateral pivoting around the lines of support.
In the above-mentioned patents, and in the description of the binding which will follow, absent any specific mention to the contrary, the relative positions of the various elements of the ski binding and the ski are understood to be relative to the direction of the normal displacement of these elements.
These types of bindings are adapted to retain the front end of the boot on the ski, while the rear end of the boot is retained on the ski by other means. This front abutment is adapted to free the boot when the release threshold of the elastic system is reached, for example, in response to excessive torsional forces on the leg. An appropriate adjustment system is also provided for the elastic energization mechanism which permits adjustment of this release threshold of the elastic mechanism.
Such a simple system responds in a entirely satisfactory fashion to a torsional fall which induces torsional movement of the boot. In such an instance, lateral pivoting of the jaw frees the boot due to lateral pivoting of the retention wings. In addition, lateral pivoting of the jaw can also be accompanied by a frontward movement of the jaw with respect to the support element, against the resistance of the elastic energization.
However, it has been discovered that such a binding is inadequate when a torsional fall is combined with a frontward fall. During a frontward fall, that portion of the sole which is directly beneath the front of the foot is pressed downwardly against the ski with a substantial force, thereby creating an appreciable friction between the sole of the boot and the ski which opposes lateral pivoting of the boot and its liberation from the jaw.
As a result, the binds described above must include a supplementary apparatus to compensate for this increased friction during a frontward and torsional fall.
For example, it has been proposed to attach a plate composed of materials having a low coefficient of friction to the upper surface of the ski. Such plates can be made, for example, of polytetrafluorethylene or polyethylene, but this type of arrangement has not been entirely satisfactory. Thus, manufacturers have attempted to find other solutions to this problem.
Another solution that has been proposed is to place a sensor beneath the front of the boot. This sensor acts on the elastic energization mechanism so as to reduce the bias against lateral pivoting produced by that elastic mechanism and is described in German Offenlegungschrift No. 2,905,837. This sensor comprises a pedal which compensates for the friction of the sole of the boot on the ski in response to pressure on the pedal by the boot during a forward fall. This is accomplished by reducing the bias of the elastic energization mechanism. Another type of binding which attempts to solve this problem is described in French Pat. No. 2,523,857, in which a moveable sensor acts on the elastic energization means.
In both of these arrangements, as well as in many other which are known to those skilled in the art, a moveable sensor acts on the elastic energization mechanism to reduce the "hardness" or bias against lateral pivoting of the jaw. These solutions have the disadvantage of requiring a relatively complex structure having numerous elements. Such a complex structure increases the cost of these bindings and increases the risk of malfunction due to freezing conditions in which they are used, due to mud which may be encountered during skiing, or as a the result of the breaking of one of the elements.
There is, therefore, a need for a binding which compensates for this additional friction resulting from an forward fall which does not increase the complexity or reduce the reliability of the binding.